"The arguments being used against AV fall into two equally flawed categories - distractions and falsehoods.

"They say you can judge someone by their friends. You can judge a voting system by its friends too," he continued.

"The friends of first-past-the-post include the BNP and the Communist party.
And the friends of AV are the Liberal Democrats, the leader of the Labour party, the Green party, Ukip, SNP, Plaid and so many people beyond politics."

The comments was met with incredulity and disdain on Twitter, where several commentators tried to turn the phrase back on Mr Clegg.

The deputy prime minister has been sidelined by the 'yes' camp out of fears that his unpopularity will discourage voters from backing AV.

Meanwhile, former home secretary John Reid insisted that the campaign against AV has been positive despite its focus on extremism and costs.

No to AV has been accused of running a relentlessly negative campaign by claiming the new system would be very expensive and allow in extremists like the BNP.

"I've certainly been trying to make - and so has John Prescott, Margaret Beckett and all of the Labour people who are supporting this, David Cameron and others - have been trying to make the positive case which I've made this morning," Lord Reid said.